issue: Undefined Constant GLOB_BRACE

This addresses issue 6079 where using `1.16.x` and PHP 8.0 on certain GNU
systems (eg. Alpine, Solaris, etc.) throws a fatal error of `Undefined
constant: "GLOB_BRACE"` when loading Plugins. This is due to `GLOB_BRACE`
not being available on said GNU systems. This removes `GLOB_BRACE` from
`include/class.plugin.php` completely as it is not used anyways.

include/class.plugin.php

@@ -251,7 +251,7 @@ static function throwException($errno, $errstr) {
      */
     static function allInfos() {
         foreach (glob(INCLUDE_DIR . 'plugins/*',
-                GLOB_NOSORT|GLOB_BRACE) as $p) {
+                GLOB_NOSORT) as $p) {
             $is_phar = false;
             if (substr($p, strlen($p) - 5) == '.phar'
                     && class_exists('Phar')